From Structural Mimicry to Functional Biomimicry: Research Progress in Sensing–Actuation Fusion Mechanisms for Soft Grippers

A soft gripper can deform around an object, yet deformation by itself tells the operator little about whether that object is held securely. This review is concerned with the ways in which grippers obtain that missing information, i.e. how sensing is coupled to actuation. It first draws on the human hand, octopus tentacles, plant tendrils and several other organisms, whose grasping involves coordinated fingers, contact receptors distributed over the body, or stiffness that changes after contact. Designs are then organized according to where the sensing element sits relative to the actuator: a separate module linked through a controller, a flexible sensor embedded in or attached to the actuator, or a sensing function provided directly by the active material. Actuation and sensing methods, together with variable-stiffness and control schemes, are discussed in terms of the working conditions each one tolerates. Examples drawn from produce handling, rehabilitation and industrial sorting are used to show why a given architecture suits a given task. Load, measurement accuracy and reliability over repeated cycles, along with the hardware these functions require, still restrict practical use. Closer integration is expected to come from multifunctional materials and data-driven control, although comparing such designs will require test protocols that studies do not yet share.